The discovery of a fossil Asian turtle in the Canadian Arctic is leading some scientists to reconsider how these animals got to America.
According to researcher John Tarduno, of the University of Rochester, the fossil suggests that tropical turtles may have reached the New World from Asia not via Alaska but by coming directly over the poles.
“We’ve known there’s been an interchange of animals between Asia and North America in the late Cretaceous period, but this is the first example we have of a fossil in the High Arctic region showing how this migration may have taken place,” he says (press release).
“We’re talking about extremely warm, ice-free conditions in the Arctic region, allowing migrations across the pole.”
James Parham, who works at the Field Museum of Natural History in Chicago and was not involved in the work, told Wired, “This paper is actually providing a route of dispersal for some of these animals. The story’s starting to slowly get pieced together.”
Tarduno says the find suggests that a ‘super-greenhouse effect’ caused by massive emissions of carbon dioxide 90 million years ago probably warmed up the poles, allowing turtles to island hop from Russia to America. Named Aurorachelys gaffneyi or the ‘aurora turtle’, the animal appears similar to a freshwater Mongolian species and probably needed these islands to cross the oceans.
“We found this turtle right on top of the last flood basalts—a large stretch of lava from a series of giant volcanic eruptions,” Tarduno says. “That leads us to believe that the warming may have been caused by volcanoes pumping tremendous amounts of carbon dioxide into the Earth’s atmosphere. There’s evidence that this volcanic activity happened all around the planet—not just the Arctic. If it all happened on a short enough timescale, it could cause a super-greenhouse effect.”
The research is due to be published in Geology.
More coverage
Turtle fossil shows how ‘super-greenhouse effect’ created tropical Arctic – Daily Telegraph
Fossil find shedding light on Arctic’s past – Canwest News Service
Image: University of Rochester